package io.zhengsh.nio.chart.server;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.TimeUnit;

// 服务端
public class ChatServer {

    // 服务启动
    public void startServer() throws IOException, InterruptedException {

        // 1、创建 Selector 选择器
        Selector selector = Selector.open();

        // 2、创建 ServerSocketChannel 通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();

        // 3、为 channel 通道绑定监听端口
        serverSocketChannel.bind(new InetSocketAddress(25000));
        // 设置非阻塞模式
        serverSocketChannel.configureBlocking(false);


        // 4、 把 channel 注册到到 selector 选择器上
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        System.out.println("服务器已经启动成功了");

        // 5、循环，等待新的连接介入
        for (; ; ) {


            // 获取 channel 数量
            int readChannels = selector.select();
            if (readChannels == 0) {
                continue;
            }

            // 获取可用的 channel
            Set<SelectionKey> selectionKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = selectionKeys.iterator();
            while (iterator.hasNext()) {
                SelectionKey selectionKey = iterator.next();

                // 移除 set 集合当前 selectionKey
                iterator.remove();


                // 6、根据就绪状态，调用对应的方法实现具体的操作
                // 6.1 如果 accept 状态
                if (selectionKey.isAcceptable()) {
                    acceptOperator(serverSocketChannel, selector);
                }
                // 6.2 如果可读状态
                else if (selectionKey.isReadable()) {
                    readOperator(selector, selectionKey);
                }
            }
            //TimeUnit.SECONDS.sleep(1);
        }


    }

    // 处理可读状态操作
    private void readOperator(Selector selector, SelectionKey selectionKey) throws IOException {
        //1 从 selectionKey 获取已经就绪的通道
        SocketChannel channel = (SocketChannel) selectionKey.channel();

        //2 创建 buffer
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        //3 循环读取客户端发送过来的信息
        int readLen = channel.read(buffer);
        String message = "";
        if (readLen > 0) {
            buffer.flip();

            // 读取内容
            message += Charset.forName("UTF-8").decode(buffer);
        }

        //4 将 channel 再次注册到选择器上，监听可读状态。
        channel.register(selector, SelectionKey.OP_READ);

        //5 把客户端发送的消息，广播到其他的客户端上
        if (message != null && message.length() > 0) {

            // 广播到其他客户端
            System.out.println("message: " + message);

            castOtherClient(message, selector, channel);
        }
    }

    // 广播到其他的客户端
    private void castOtherClient(String message, Selector selector, SocketChannel channel) throws IOException {
        // 1 获取所有已经接入的客户端
        Set<SelectionKey> keys = selector.keys();

        // 2 循环向所有的 channel 广播消息
        for (SelectionKey selectionKey : keys) {
            // 获取里面的每个通道

            SelectableChannel otherChannel = selectionKey.channel();
            // 不需要给自己发送
            if (otherChannel instanceof SocketChannel &&
                    channel != otherChannel) {
                ((SocketChannel) otherChannel).write(Charset.forName("UTF-8").encode(message));
            }
        }

    }

    // 处理接入状态操作
    private void acceptOperator(ServerSocketChannel serverSocketChannel, Selector selector) throws IOException {
        // 1 接入状态，状态 创建 socketChannel
        SocketChannel socketChannel = serverSocketChannel.accept();

        // 2 把 socketChannel 设置为非阻塞模式
        socketChannel.configureBlocking(false);

        // 3 把 channel 注册到 selector 选择器上，监听可读状态
        socketChannel.register(selector, SelectionKey.OP_READ);

        // 4 客户端回复信息
        socketChannel.write(Charset.forName("UTF-8").encode("欢迎进入聊天室！"));

    }

    public static void main(String[] args) throws IOException, InterruptedException {
        ChatServer chatServer = new ChatServer();
        chatServer.startServer();
    }
}
